In producing a glass bottle, a crack such as crazing may be sometimes formed in a wall thickness of a bottle-mouth portion. This crack is referred to as a check. The location of the bottle-mouth portion where a check is generated is limited to some extent, and typically there are a mouth-check generated in the top surface or near the top surface of the bottle mouth, a screw-check generated in a screw thread portion of the bottle mouth, and a neck-check generated in a neck portion of the bottle mouth. Further, depending on the direction of the crack, the checks are classified into a vertical check extending in a vertical direction (substantially vertical direction), a lateral check extending in a lateral direction (substantially horizontal direction), and a skew check extending in an oblique direction.
Because the above-mentioned check can cause damage to the glass bottle, the presence or absence of a check is detected by imaging the bottle-mouth portion, and the glass bottle having the check is removed as a defective bottle.
Conventionally, there has been known an inspecting apparatus for inspecting a check of a glass bottle which can inspect the presence or absence of a check automatically by imaging a bottle-mouth portion of a glass bottle. The check inspecting apparatus comprises plural pairs of light-emitting units and light-receiving units which are arranged so as to surround the bottle-mouth portion of the glass bottle, and the plural pairs of the light-emitting units and the light-receiving units are adjusted and arranged in an optimum position with respect to the bottle-mouth portion of the glass bottle to be inspected. Then, reflected light from the glass bottle is received by each pair of the light-emitting unit and the light-receiving unit, and the obtained signals are processed to detect a check in the bottle-mouth portion. In this case, light emitted from the light-emitting unit is applied to the bottle-mouth portion, and if there is a check, the light is reflected by a crack plane of the check and is thus illuminated brightly. Therefore, the reflected light is received by the light-receiving unit which is the companion to the light-emitting unit, and the check of the bottle portion is detected by judging the presence or absence of a portion having brightness of a predetermined value or more.
The above-mentioned conventional check inspection apparatus has plural inspection stations for inspecting a check in the bottle-mouth portion of the glass bottle, and the glass bottle is held and conveyed along a circumference by a star wheel for inspection, and is then indexed in the plural inspection stations. In the plural inspection stations, while the glass bottle is rotated about its own axis, the glass bottle is inspected to detect each defect such as a mouth-check, a screw-check, or a neck-check individually.
The above-mentioned conventional check inspection apparatus is constructed so that plural inspection stations are provided, and plural pairs of light-emitting units and light-receiving units are arranged in each of the inspection stations. Therefore, when the type of glass bottle to be inspected is changed, the arrangement of the plural pairs of the light-emitting units and the light-receiving units must be readjusted in each of the inspection stations. Specifically, angles and heights of the plural pairs of the light-emitting units and the light-receiving units in each of the inspection stations must be readjusted, and the sensitivity and the like of the light-receiving unit must be readjusted.
Further, in the glass bottle having a screw thread portion on a bottle-mouth portion, the screw thread portion has complicated curved surfaces. Therefore, in many cases, reflected light similar to the reflected light caused by the check is produced in the screw thread portion. However, even if the reflected light is produced from an area where the screw thread portion is located, processing is carried out so as not to judge that there is a check. Therefore, even if there is a check in the screw thread portion and areas above and below the screw thread portion, such a check cannot be detected. Further, the seam portion of the bottle is formed into a curved surface extending continuously in the vertical direction. Therefore, in many cases, reflected light similar to the reflected light caused by the check is produced in this seam portion. Thus, the same processing as in the screw thread portion is carried out in this seam portion. Consequently, even if there is a check in the seam portion and an area around the seam portion, such a check cannot be detected. That is, in a specific part of a glass bottle, even if the glass bottle is normal, an image of the normal glass bottle which has been imaged by a light-receiving unit becomes the same image as a defective glass bottle. Thus, a non-defective bottle and a defective bottle cannot be distinguished from each other. Further, conventionally, it is difficult to detect a molding failure in the screw thread portion or the like which is generated in molding a bottle.
Therefore, there has been a demand for a glass bottle inspecting apparatus which can detect defects at a specific location of a glass bottle such as a defect in areas located above and below a screw thread portion or a defect located around a seam portion of the bottle, and a molding failure in the bottle (particularly, the screw thread portion) without a need for readjustment of the arrangement of light-emitting units and light-receiving units when the type of glass bottle to be inspected is changed.